Glass setting are somewhat a matter of taste, but some guidelines below. The Portal option in Indirect Lighting allows light through the glass. I might also experiment with a backlit shader and not glass.
In order for light rays to bend correctly, Glass requires two surfaces; glass objects should be a 3D Object, not a simple 3D Polygon. Without a second surface, the light will bend as if it is going into glass, but not bend back.
When creating glass for a window, Press the Indirect Lighting Options button in the Texture Definition Dialog. There, choose Portal and Emit Light.